450 PROTEIN POISONS 



gators produced evidence of the fact that the intra- and 

 extracellular germicidal constituents of the blood are not 

 identical, but since the literature of this subject has been 

 collected by Kling, 3 we will not go into detail but will 

 content ourselves with the reproduction of the summary as 

 given by this author. It should be stated that Petterssen 

 designates the intracellular germicidal constituent of leuko- 

 cytes and other cells as "endolysins." Kling's conclusions 

 from the .work of others and himself are stated substantially 

 as follows: (1) The germicidal substances (endolysins) 

 of the polymorphonuclear leukocytes may be obtained 

 from the protoplasm by the following methods: (a) By 

 digesting the cells for half an hour at 50 in bouillon. (6) 

 by extracting the cells with weak acid or alkali, or (c) by 

 alternating freezing and thawing of the cells. They cannot 

 be obtained by digesting with bouillon at 37, nor with 

 physiological salt solution, nor with 5 per cent, "inacti- 

 vated" serum. (2) As tested on bacillus subtilis, the 

 endolysin bears a temperature of 65 without recognizable 

 effect on its germicidal action, and it is not until the tem- 

 perature is increased to 75 that any such effect is noticed. 

 The endolysins can, in daylight at room temperature, and 

 in the dark at 37, be evaporated to dryness, and in this 

 state they may be heated for half an hour at 100 without 

 being destroyed. The serum alexins may be obtained in 

 the dry state in the same manner, but when heated to this 

 temperature they are inactivated. The endolysin as tested 

 on the subtilis does not pass through a Pukall filter, while 

 the serum alexin does. The endolysins as tested on the 

 subtilis, the anthrax, and the typhoid bacillus are destroyed 

 by the Rontgen ray, while the serum alexins are not. The 

 endolysins cannot be extracted with ether, but are not 

 injured by ether, while the serum alexins are destroyed by 

 ether. (3) The activity of an inactivated extract of the 

 leukocytes of the rabbit, as tested on the subtilis, may 

 be restored by the addition of a small quantity of the same 



3 Zeitsch, f, Immunitatsforschung, 1910, vii, 1. 



